#define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

int max3(int x, int y, int z)
{
	int c = x > y ? x : y;
	return z > c ? z : c;
}

int main()
{
	int a = 0;
	int b = 0;
	int c = 0;
	scanf("%d%d%d", &a, &b, &c);
	double m = 1.0 * max3(a + b, b, c) / (max3(a, b + c, c) + max3(a, b, b + c));
	printf("%.2lf\n", m);
	return 0;
}